An undercover operation to stop drug dealing at two Riverside County high schools has ended with about two dozen arrests.

The Riverside Press-Enterprise says 22 arrests were made Thursday at Paloma Valley High in Menifee and at Perris High. Three students still are being sought.

The arrests followed a semester-long operation in which two sheriff's deputies posed as students. Authorities say most arrests were for dealing small amounts of marijuana but cocaine, methamphetamine and prescription pills also were seized.

Students told the Press-Enterprise that officers with photos of the suspects came into classrooms and handcuffed them in front of classmates.

A similar probe last year led to around two dozen arrests at two schools in Temecula. One arrest involving an autistic student has prompted a lawsuit.